1. Field of the Disclosure
This disclosure relates to a filling apparatus for a grouting system, a method for adjusting gel time of a grouting system used for anchoring a reinforcing member, e.g., bolts and other supports, in a mine, a grouting system for anchoring a reinforcing member in a mine, and a method of anchoring a reinforcing member in a mine.
2. Discussion of the Background Art
Anchor bolts are employed in various fields of engineering, for example, as strengthening or reinforcing members in rock formations and in structural bodies. The bolts are inserted into drill holes in the formation or body, and often are fixed or anchored, at their inner end or over substantially their entire length, by means of a reactive chemical grouting composition that hardens around the bolt. When used in a mine roof, bolts grouted in this manner help significantly to prevent mine roof failure.
A chemical anchor grouting composition can contain a polyester resin mastic and an initiator separated by barrier until time of use. Such a two component chemical anchor grouting composition is typically placed in boreholes using tubular compartmented capsules, also known as resin cartridges. A bolt is inserted in the hole and rotated which ruptures the cartridge and allows the two components to mix. The bolt is held in position until the resin grout sets to permanently hold the bolt in place. It is sometimes advantageous to the rock reinforcement to apply a tension load to a bolt after it is installed.
For a bolt that uses a resin grout composition to secure it and the grout covers the entire length of the bolt, and there is a need to place part of the bolt in tension, than a grouting composition with two gel times is required. A fast gel time resin is used in the inner end of the hole to set quickly and grout approximately half of the bolt. A slow gel time resin grout is used in the remainder of the hole. The sequence for installation in a typical resin grouted bolt to be pre-tensioned is to spin the bolt to mix the two components of a resin cartridge, wait for the fast resin to set to secure the bolt in position, use a mechanical tensioning device such as a threaded coupler or nut to apply a tension load to the bolt, and then the slower resin grout sets to secure the remainder of the bolt and prevent the tension force from bleeding off.
Mining and tunneling industries have traditionally used two cartridges of resin grout for anchor bolts that are pre-tensioned, with one cartridge being fully a fast gel time resin and one cartridge being fully a slow gel time resin. It is advantageous for the end user to be able to install a single cartridge that contains both a fast and slow gel time resin grouts instead of having to maintain and install both a fast and a slow resin cartridge. A single resin cartridge with both a fast and slow component, often described as a two-speed cartridge, has been used for a number of years. The most common method for manufacturing a two-speed cartridge is to have two alternating pumps supplying a portion of the cartridge with fast resin mastic and then the remainder as slow resin mastic. That method requires capital investment for two sets of mixing and pumping equipment for manufacturing a two-speed cartridge.
For example, two-speed resin cartridges are conventionally produced by making two resin mastics at different gel times and then using an alternating pumping system that switches the resin feed to the cartridge fill tube back and forth between the resin mastics of two different gel times. The disadvantage to the conventional method is the resin mastic is difficult to pump and a dual pumping system is expensive for initial setup and maintenance. Two setups of the full pumping systems are required to make a chemical anchor with two gel times. The ingredient cost is also higher for a two gel time cartridge because a higher purity white ground calcium carbonate is used for the filler; so that, one of the resin mastics can be fully colored to indicate the different gel times in the cartridge. Resin mastic made with a lower cost gray ground calcium carbonate cannot be colored due to the black influence of impurities in the calcium carbonate.
There is a need in the art for a low cost cartridge with two gel times in the same cartridge. There is a need to clearly show in such cartridges which end of the cartridge has the slow gel time so as to prevent incorrect installation in a mine. There is also a need in the art for a cost effective cartridge filling system that does not require multiple resin pumps, e.g., pumps for fast resin mastic and slow resin mastic.
The present disclosure provides many advantages, which shall become apparent as described below.